Nimble ballerinas and long-legged birds are elegant; dump trucks and walruses usually are not.
Being graceful and refined are aspects of being elegant. That word first appears in English in the 15th century. It comes, via Old French, from the same Latin source that gave rise to the English word "elect, and it does seem that especially elegant people and things are in a select group. Very stylishly dressed men and women are elegant, and fine restaurants with distinctive delicacies are elegant. Most ordinary places and people can become elegant, though, when dressed up or adorned for special occasions. Even walruses can appear elegant when they're swimming.